Lyman GPR

[uscglechief]

Greetings all,

I scanned the topic list and didn't see anything on GPR. I recently ordered my first muzzleloader,a LH GPR, and am anxiously awaiting its arrival. My question is can someone advise of where I should start with my loads?

Thanks and sorry if this is a repeat topic.

Jesse

 

[Sperit de bois]

First read the Owners Manual, O/M, great rifle,I have one in left 50 cal percussion,some sweet handling. So say it's heavy,,well who is going to carry that 300lb saber toothed deer,if you cant carry the rifle,,we all shoot them, ,,dont we??
I run 90 grn Pyrodex P in mine PRB. Following the O/M and if you decide to go fast twist GPH ,you can order the 1/32 barrel and it drops right in.
If you go to the top,"SEARCH" then Quick Search, type in GPR and see what comes up.
That said, come early, stay late and introduce yourself.

 

[Lonegun1894]

I use 70grs FFFg in my .50 and 80grs FFFg in my .54, both with PRBs, and both shoot great. I think you chose a great one there. Not too many complaints about these rifles. I have 3 of them, all flint.

 

[Greenjoytj]

What caliber did you order?

My GPR is .54 cal.

My load is 90 grain of Goex 2fg with a over sized .58 cal. over powder wad that has been soaked in melted mink oil grease.

Then a 0.0175" 100% heavy white cotton twill cloth patch that I cut out in a circle shape 1 & 5/16" dia. (the patch material has been washed twice in cold water to get out the sizing and dried at cool temperature so as not to shrink the fabric. This fabric will squash down to 0.0095" with a micrometer fairly heavily tightened down. The seventeen and a half thou is measured with the micrometer letting the clutch slip in the normal fashion.

My ball is pure lead that I cast my self and is .5365" (nominal .535" Lee mold )and weighs ~231 grains.
I sort balls to + - .2 grains from the average ball wight.

My bore/patch/ball combination seem to be a perfect fit as I can see a good pattern of the cloth weave gets embossed all around the circumference of the ball, heavy at the lands and lightly at the grooves.

My GPR cut up the patches for about the first 70 shots even though I use JB bore shine paste while cleaning specifically to help buff off the very sharp edges of the rifling.

Now that I have a little over 100 shots through the bore I am not getting any cut up patches and my 5 shot groups are under 2" at 50 yds and usually 3 of the bullet hole will be touching each other. I have a Lyman 57GPR receiver peep sights mounted and the matching globe front sight. Concentrating on the peep sight picture helps me forget about the pan flash.

I am using Thompson Center cut agate flints and get about 18-20 shots before I have lack of spark to light the 4 fg priming. I can flip these flints over and keep shooting. I also resharpen them with a flat diamond grit file in a pan of water.

The PRB combo I mentioned above is not easy to start into the bore. I can do it pounding my balled fist onto the short starter, but I prefer to save my hand and us a light weight 10 oz dead blow hammer on the short starter. I have no problem seating the ball with my solid brass range rod (a must have item).

Priming is easy with with one of those brass tube priming flasks with the spring loading tip that dispenses 3-4 grains of 4fg per push on the tip.

Keep your flint sharp, and properly adjusted for strike height on the frizzen face and ~1/16" away from the frizzen at 1/2 cock notch. Keep the frizzen and flint clean of fouling smoke residue.
Clean out the flash hole every 4 or 5 shots. Damp wipe the barrel one time between shots.

Don't tighten up the single screw that hold the lock plate to the stock too tightly or you my find that it will prevent the set trigger function from working.

Remember the butt plate on that rifle is lethal to the shooter if mounted to the shoulder don't do that, it is designed to be mounted further off the shoulder, out onto the arm at shoulder joint.

I prefer to take pre filled RMC EC view quick load tubes of powder to the range rather than measure out the load at the range.

To clean the rifle after shooting, I clean the stock first and then lock and last cleaned is the barrel in cool water at the laundry tube. Removing the vent liner and running water down beside the cleaning rod works great to flush the fouling out the 6mm vent hole. Use a 36 cal brush to clean down into the patent chamber area of this rifle and make of a wood dowel with a slit in the end to take a patch down into that 36 cal chamber. Re install the vent liner with anti seize compound.

I am using an RMC vent liner designed for the metric threaded 6mm vent hole in the barrel.

Good luck this you GPR.

 

[damron]

caliber?

 

[William O.]

I have a LH 50 caliber GPR that I have not yet sighted in but I will start with a 50 grain charge of 3f Goex. Usually it is best to start with 1 grain per caliber, so if you have a .54 then start with 55 grains. What you want to do is first find the best powder charge for you rifle by shooting three to five times then increasing by 5 grains and repeat until your groups get nice and close together. It's only then that you adjust your sights or change other varibles such as patch thickness, type of lube, etc. I also recommend swabbing the bore with an alcohol dampened patch between shots to return things to as close to the same as you can.
One thing I have observed with Lyman barrels is that they usually need to have the bore polished before they really start to have great accuracy and there are several ways to accomplish this. You can just shoot it in which will take 100 or so shots, wrap some OOOO steel wool around the cleaning jag and run it in and out of the barrel a couple dozen times or apply some kind of polishing compound to a cleaning patch and run it down the bore the same way. You can even fire-lap the bore by loading and shooting a couple of specially coated bullets. Now, when I say that Lyman barrels usually don't exhibit their best accuracy until the bore is polished I don't mean that it's a difference of a foot or more. They just seem to get more accurate after a good polishing or 100 shots, that's all. It could be an inch at 100 yards, it could be less.
Anyway, your new GPR should be a good solid performer and will last you a lifetime, you made a good choice.

 

[jbtusa]

Take the trigger set screw to Ace hardware and get a longer one, then file it down to where it works (it's metric).

Don't forget to squirt WD 40 into the hairline gap between the barrel and barrel lug to keep out the rust after a water bath.

Lastly, shoot it 200+ times to settle the barrel. Then it will settle down into an excellent shooter. You will grow to love that rifle!

 

[FRJ]

Hi Stryk, I have a 54cal GPR in percussion and I use 65gr 2F for plinking and target loads.This is with a .015" pillow ticking patch lubed with 20/10 WSW fluid and a cast lead ball of .537". For hunting I just finalized my hunting load at 110 gr of 2f with a .125 felt wad over that and a .015 pillow ticking patch lubed with TOW mink oil and a home cast .537" ball. Your rifle will probably be different but these are the loads I use. FRJ

 

[humpy blaster]

Hi STRYK
I have three gprs one is a flint in 54 the load i use in the 54 is 95 gr 2f goex with a 0.15 pillow tick patch.I regularly shoot groups off the bench of 1.3 in.with open sights and i know that this is real good for a flint gun. If you are seeing the flash of the prime you arent going to hit anything.Also on the lyman gun you need a healthy charge for the prime, best to the bottom of the touch hole. As many here will remember I personally had fits with my flint gun and was thinking about giving up on it.Turned out that i was too cheap on the prime now i impress the modern day shooters with my flint gun.No it doesnt shoot with my 300 sm but it is plenty accurate for gophers to 125 yds.

 

[humpy blaster]

Hi stryk
sorry almost forgot most important part dump the factory touch hole liner.I went for the rms but next would go for the white lightning liner.tight groups.
stump shooter

 

[hthomso]

My .50 GPR flinter likes 70gr 3f Goex with a .490 ball patched with a .015 cotton patch lubed with Bore Butter. I use 3f for prime as well. I also replaced factory vent liner with an RMC liner. Works great. I think you will like the GPR. One of the best values for the money. Plenty of disucssion on the MLF about the GPR. Happy shooting. :thumbsup:

 

[droptine55]

welcome aboard stryk, we`ll get you squared away here in a few weeks at the PTHC

 

[pa woods roamer]

Stump Shooter...Heartily agree on the healthy charge of Pan Powder!! My .50 GPR was also giving me fits. The Pan would Flash but no Barrel ignition. I finally remembered I had a T/C that did the same thing. You always had to fill the Pan on it also to get it to go off.Tried it out today and it went off with no noticeable delay...Life is good again.

 

[Darkgael]

GPR - best value dollar for dollar.
Mine is a .50 cal and has given me quarter sized groups at 100 yards. (90 grs. FFg Goex. PRB 0.010 patch. Prime with FFFg ) I drilled out the flash hole a tad.
I also picked up a .54 cal smoothbore barrel from Green Mt. Nice.
Pete

 

[uscglechief]

Sorry all,

I was in a hurry to leave work and haul butt to PA for a mini vacation, the GPR I ordered is .54, I'll read thru all posts and reply.

FYI, I tried to get 4F powder at Gandermountain store in PA and was told that its currently unavailable due to a fire/explosion at the plant.

 

[uscglechief]

Sorry I didn't post the first time, yes ordered a .54 cal, should be in this week. Very much looking forward to firing this gun.

Jess

 

[BrownBear]

Don't worry about the 4f. Mine works just fine with 3f for prime and actually prefers the 3f in the bore for accuracy. One horn does it all for me.

 

[uscglechief]

Many thanks, been told I could work it that way with the 3F.

 

[wcontratto]

Didn't see anyone else mention this, so I will.

When you clean your GPR, remember that it has a patent breach. I use a smaller caliber bronze brush to de-gunkify mine. As mine is .50 cal, I'm not sure what size to use on a .54

 

[Swede50]

Gandermountian does not carry Black Powder here in Kansas. I have been not to try to shoot Pyrodex or 777 in my flintlock something about it not wanting to go off.